1. Field of the Invention
The present invention relates to a key-operated arrangement, and more particularly to an arrangement for teleprinters.
2. Description of the Prior Art
Key-operated arrangements encode characters and data with the help of a keyboard arranged in matrix fashion in rows and columns and using an addressable fixed-value store and a scanner device which periodically scans the keyboard by row and column lines and the fixed-value store by row and column lines. If a signal produced by the operation of a key in the keyboard is present, the scanner device produces the coded character corresponding to this key from the store.
In modern keyboards for electronic teleprinters, complete electronic control is carried out in a highly integrated MOS module. The mechanical portion is generally restricted to a key matrix with a key and associated make contact which connects a diode at the particular matrix point. In order to make this kind of highly integrated MOS module as versatile in application as possible, this kind of keyboard module must incorporate virtually all the functions which are likely to occur within a wide range of applications. Naturally, driving of this kind of module through a restricted (because of the sizes involved) number of connecting pins (which results because of the sizes involved) constitutes a major problem. The layout of this kind of module must be so designed that it can be driven using the minimum number of connecting pins.
The heart of a finished keyboard module consists of a character store which is generally designed to have several levels and contains the characters which can be called up by means of keys. In this context (as known from German Letters Patent No. 2 153 108) the keyboard matrix is periodically scanned by a counter device and, if there is a closed key, the data corresponding to the key is prepared in the store. In the particular case of a teleprinter, this means that with actuation of a key, the stored data corresponding to the character is supplied to the teleprinter transmitter. This data is, of course, coded in accordance with the particular code being used.